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Optics-Lasers - Patricia Bath

Light rays enter the eye through the cornea, the clear front “window” of the eye. The cornea’s refractive power bends the light rays in such a way that they pass freely through the pupil (the black spot in the center) the opening in the center of the iris through which light enters the eye.

The iris (the colored part of the eye) has the ability to enlarge and shrink, depending on how much light is entering the eye.

After passing through the iris, the light rays pass thru the eye’s natural crystalline lens. This clear, flexible structure works like the lens in a camera to focus the light rays properly. Sometimes and especially as the eye ages, this doesn’t work perfectly.  In many of these situations, the vision can be sharpened through the use of eye glasses.

In a normal eye, the light rays come to a sharp focusing point on the retina. The retina functions much like the film in a camera. It is responsible for capturing all of the light rays, processing them into light impulses through millions of tiny nerve endings, and then sending these light impulses through over a million nerve fibers to the optic nerve.

In summary, the cornea is the clear, transparent front covering which admits light and begins the refractive process. It also keeps foreign particles from entering the eye.


The pupil is an adjustable opening that controls the intensity of light permitted to strike the lens.

The retina receives the image that the cornea focuses through the eye’s internal lens and transforms this image into electrical impulses that are carried by the optic nerve to the brain.




Cataracts are cloudy blemishes that form in the lens of a person’s eye, and they are most commonly seen in people over the age of sixty. 

The Laserphaco Probe

Patricia Bath’s Laserphaco Probe improved on the surgery that was used to remove cataracts.

The probe “consists of an optical laser fiber surrounded by irrigation and aspiration (suction) tubes. The excimer laser probe can be inserted in a tiny (1 mm) incision in the eye. The laser energy phacoblates (vaporizers) the cataract and lens matter within a few minutes. The decomposing lens is extracted when liquid supplied by the irrigation (water) line washes through and is sucked out through the aspiration (suction) tube, and a replacement lens is inserted.”

How does a Laser Work?

An excimer laser typically uses a combination of a noble gas (argon (AR), krypton (KR), or xenon (XE) and a reactive gas (fluorine (F) or chlorine (Cl)). Under the appropriate conditions of electrical stimulation and high pressure, a pseudo-molecule (excimer) is fleetingly created, and gives rise to laser light in the ultraviolet range as it decomposes.

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